Vitamin D and ER levels of expression and other clinicopathologic characteristics in breast cancers

Background Vitamin D is a steroid hormone with many vital physiological functions. There is extensive research suggesting that vitamin D additionally acts as a protective factor against the development and progression of breast cancer. However, there is limited detail regarding the effect of vitamin D insufficiency or deficiency on the clinicopathologic characteristics of breast cancer.Methods A retrospective analysis of all the breast cancer patients that had received treatment at the Algoma District Cancer Program, Ontario, Canada between 2016 and 2024 was conducted. Patients were grouped according to their circulating 25-hydroxyvitamin D levels as sufficient (25-hydroxyvitamin D- 25-OHD ≥ 75 nmol/L) or insufficient (25-OHD < 75 nmol/L). The groups were compared for demographic and tumor characteristics along with outcomes. An analysis according to 25-OHD deficiency (25-OHD < 50 nmol/L) was also performed.Results Patients with vitamin D sufficiency represented 55.7% (295 of 530 patients) of the whole cohort, while patients with vitamin D insufficiency represented 44.3% (235 of 530 patients) in the cohort. Patients with vitamin D sufficiency were older, less likely to be obese, and were more likely to have tumors with high estrogen receptor (ER) expression. Vitamin D insufficient patients had shorter overall survival (LogRank test p = .02). The association, however, was lost on the multivariate analysis.Conclusions Vitamin D sufficiency in breast cancer patients is associated with older age and lower obesity rates, along with favorable tumor prognostic indicators like high ER expression. Maintaining vitamin D sufficiency may improve breast cancer outcomes.